1. Field of the Invention
The present invention relates to an image information readout exposure apparatus comprising a first light source, for performing readout scanning exposure on an image information recording medium, on which image information is recordable as an electrostatic latent image, to read out image information recorded thereon; and a second light source, for performing scanning exposure, which is different from the readout scanning exposure performed by the first light source, on the image information recording medium.
2. Description of the Related Art
Conventionally, there are known image information readout exposure apparatuses. These apparatuses comprise a first light source, for performing readout scanning exposure on an image information recording medium, on which image information is recorded as an electrostatic latent image, to read out image information recorded thereon; and a second light source, for performing scanning exposure, which is different from the readout scanning exposure performed by the first light source, on the image information recording medium.
For example, in medical radiation imaging and the like, image recording media comprising photoconductive bodies such as selenium plates are employed. This is to reduce the amount of radiation that a subject is exposed to, and to improve diagnostic properties. Radiation, which has passed through the subject, is irradiated onto the image recording medium, to accumulate charges corresponding to the amount of radiation irradiated thereon. The accumulated charges are stored in a charge accumulating portion of the image recording medium, thereby recording a radiation image as an electrostatic latent image. During readout of image information, a readout light, such as a laser beam or a line light, is scanned and exposed on the image recording medium by an image information readout exposure apparatus. Thereby, the image information (electrostatic latent image) is read out.
It is often the case that exposure to erase charges or dark current charges is performed (as disclosed in U.S. Pat. No. 6,268,614 and U.S. Patent Laid-Open No. 20010030305), in order to improve the readout accuracy of image information. Alternatively, exposure may be performed to cause optical fatigue prior to recording (as disclosed in U.S. Pat. No. 6,373,063). In addition, there are cases in which exposure to obtain a readout range or dark current correction data is performed prior to the readout scanning exposure.
A planar light source may be employed as the second light source for performing exposure, which is different from the readout scanning exposure. However, it is desirable, from the viewpoint of cost, that a line light source or a point light source be employed. On the other hand, in the case that a line light source or a point light source is employed, a separated scanning means, for scanning these light sources, becomes necessary. Therefore, there is a problem that the use of these light sources is a barrier to lowering the manufacturing cost of an exposure apparatus.